This invention relates generally to welding, or positioning, fixtures suitable for fabricating weldable workpieces to close dimensional tolerances, and particularly relates to a welding/positioning fixture apparatus especially suitable for precise alignment and fabrication of weldable fluid piping manifolds.
Very close dimensional tolerances are required in the fabrication and welding of fluid piping manifolds having flanges that are bolted, or otherwise connected, to other manifolds having matching flanges and/or are attached directly to associated equipment such as high pressure liquid pumping systems used for example in the production of oil and gas. Maintaining close tolerances in the fabrication and welding of such manifolds enhances the interchangeability and serviceability of the manifolds in the field as well as reducing the manufacturing and assembly lead time for systems employing such manifolds. Prior art welding fixtures are typically used to position various sections of a workpiece in place before and during tack-welding thereof to form a unitary structure that can be fully welded either prior to removing the workpiece from the fixture, or after removing the workpiece from the fixture. The use of the terms welding and positioning with respect to fixtures are considered to be interchangeable herein. By using such fixtures, the dimensional tolerances of the workpiece are usually held within acceptable limits. Furthermore, the use of such fixtures reduce production costs because welding equipment operators spend considerably less time positioning and welding individual subcomponents of the workpieces together with the aid of a fixture as compared to welding the pieces together free handedly.
In the case of fabricating and welding fluid piping manifolds to strict dimensional requirements, such as those required for manifolds to be used in high pressure pumping systems typically used in the production of oil and gas reserves, a conventional fixture would be built to accommodate the particular manifold geometry set forth in the detailed manufacturing drawings of that particular manifold. A representative prior art fixture 4 having such a manifold 2 positioned therein is shown in FIGS. 1A and 1B of the drawings. As can be seen in FIGS. 1A and 1B, the particular manifold 2 shown consists of a hollow straight pipe section 10, an intersecting pipe 9, and an elbow 11. Horizontal flanges 12 are located at the free ends of pipe 9 and elbow 11. Flanges 12 are located on the base of the fixture by locating pins and/or bolts. Upright member 6 supports manifold end 13 by way of coupling 8. After so positioning the various components the welding operator may proceed to tack weld the components together and if desired, perform the final welding required to complete the manifold. Thus, if a manifold requires strict dimensional tolerances, the fixture to be used in the fabrication and welding of that manifold would have to be made to even more exacting tolerances to insure that each manifold fabricated within the fixture met the tolerances set forth in the manufacturing drawings. Although such conventional fixtures are effective, the fixtures are costly and time consuming to build and are also costly and time consuming to revise as design changes are made to the manifold in which a particular fixture is used, especially in the case of manifolds having complex configurations. In addition to the costs of building the fixtures, the use of the fixture is typically limited to one particular manifold geometry of a particular size making it necessary not only to build a fixture for each manifold geometry or size, but also making it necessary to store, retrieve, and set up a particular manifold-specific fixture when that particular manifold is produced on less than a full-time basis at a given fabricating/welding station.
Therefore, it is an object of the disclosed invention to reduce the costs associated with building, revising, storing, and retrieving welding fixtures designed to accommodate a specific workpiece having a specific geometry.
It is a further object of the disclosed invention to provide a welding fixture apparatus that can be easily adapted to accommodate a wide variety of workpieces having a wide variety of geometrical configurations and sizes.
It is a yet further object of the disclosed invention to provide a welding fixture apparatus that will maintain close tolerance dimensioning between fabricated workpieces.
These and other objects and benefits of the disclosed invention will be discussed and depicted in the specification and the drawings hereof.